marginal utility of juice rises sufficiently that Equation 6-2 is restored. In
other words, her utility-maximizing response to a higher price is to
reduce her quantity of juice demanded, which of course implies a
negatively sloped demand curve.
This analysis leads to the basic prediction of demand theory:
A rise in the price of a product (with all other determinants of demand held constant) leads
each utility-maximizing consumer to reduce the quantity demanded of the product.